Ventilator caps are widely used to facilitate venting from gas exhaust outlets on building roofs and transportation vehicles. For example, recreational vehicles utilize a holding tank for storage and processing of sewage (black water) and/or grey water. Such holding tanks are generally vented to the exterior atmosphere by a vent pipe which typically exits the vehicle through the roof of the vehicle. A cap is provided on the vent pipe to prevent objects from entering the pipe. However, the unpleasant odors can accumulate in the holding tank and seep back into the living area of the vehicle.
To improve and facilitate the exhaust of gases from the holding tank, a rotating vent cap resembling a wind vane has been used to take advantage of wind movement. Such vent caps are pivotally connected to the outlet of the vent pipe and have a vane which causes the outlet opening to point downwind, thereby drawing vapors from the holding tank. A drawback of such vent caps however is that they require a certain minimum wind velocity to function effectively, in particular at least enough wind velocity to pivot the wind vane. In the absence of that minimum wind force, the device may not function.
Other venting apparatus are shown in the following U.S. Pat. No. 55,094 Hardy; U.S. Pat. No. 3,302,552 Walsh; U.S. Pat. Nos. 3,347,147 and 3,382,792 Howard; U.S. Pat. No. 3,509,811 Topp; U.S. Pat. No. 4,531,455 Palmer; and U.S. Pat. No. 4,603,619 Amphoux.
It is therefore desired to provide a vent cap which functions to improve the exhaust of gasses from holding tanks, attics, stacks, chimneys or the like omni-directionally with no moving parts and even in conditions of low velocity air movement.